Improvement in cutter-heads



J. DuBOIS.

CUTTER-HEAD.

No. 192,242, 'Patented June 19,1877.

JAM;

WASHINGTON D C "Jrvrrnn snares JOHN DU BOIS, OF WILLIAMSPORT,PENNSYLVANIA.

IMPROVEMENT IN CUTTER-HEADS.

specification forming part of Letters Patent No. 592,242, dated June 19,1877 application filed August 7, 1876. 4

To all whom it may concern Be it known that I, JOHN DU BOIS, ofWilliamsport, in the county of Lycoming and State of Pennsylvania, haveinvented certain new and useful Improvements in Gutter-Heads, of whichthe following is a specification:

My invention relates to that class of cntterheads in which removablebits or cutters are employed and consists in the combination of twoclamping-plates having circular concentric grooves in their inner faces,with bits having their ends seated in said grooves and their outer facescurved in the arc of a circle eccentric to the axis of the head; andalso in providing one of the clamping-plates with a central tubular neckpassing through the other plate and provided with a screw-thread toreceive a nut by which the plates are forced together upon the bits.

Figure 1 represents a side view of my head with one of theclamping-plates removed to expose the ends of the bits; Fig. 2, acentral cross-section of the head in a line with its axis; Fig. 3, asimilar sect-ion through one edge of the head, showing another form ofbit therein; Figs. 4, 5, and 6, face views of three dili'erent forms ofbits to be used in the heads.

A and A represent two flat circular-plates, provided in their innerfaces with circular concentric grooves a near their outer edges, asshown. The plate A is also provided at its center with a tubular neck orsleeve, 0, passing through a central hole in the plate A, and providedwith an external screw-thread to receive a nut, B, which bears upon theoutside of the plate A, as shown in Fig. 2, so as to force the platestightly upon the bits or cutters. D represents the bits or cutters, twoor more of which may be used in each head. Each bit consists of a thincurved steel plate having its ends provided with curved ribs' 1), whichare seated in the grooves of the clamping-plates, as shown in Figs. 2and 3, so as to hold the bits firmly and immovably in 'the head when thenut is tightened up. Each bit has its outer surface curved in the arc ofa circle from its cutting-edge slightlyinward toward the axis or centerof the head, in order that the knives may have a free clearance and thatthey may not come in contact with the wood except at their edges. Thecuttingedges of the bits are inclined or beveled latl erally, in orderto cause them to cut cleanly and evenly in all woods and under allcircumstances.

The bits, curved and mounted in the manner shown and described, arecheap and durable, and need no adjusting whatever, as the seating oftheir ends in the annular grooves brings them at once in the preciseposition required. The bits are sharpened by simply grinding away theircutting ends on the inside, and as they are all made of precisely thesame form and size it follows that when they are all ground to the samelength and seated in the grooves their edges must all be at preciselythe same distance from the center of the head, and consequently thatthey will all cut in precisely the same plane. and thereby pro ducesmooth and finished work. As the knives are ground away and shortened,the diameter ofthe head will, of course, be diminished, but so long asall the knives of the head are of a length they will cut in the sameplane.

In order, therefore, to insure the proper action of my knives, it isonly necessary to grind them to the same length and seat them in thegrooves, which bring them at once to their proper positions withoutrequiring any adjust- 'ment.

This construction of my head, so that the knives do not requireadjustment radially in the head, but merely to be of a uniform length,is of great importance, inasmuch as the grinding of my detached bits orknives to gage is a very simple and easy matter, while, on the contrary,the adjustment of the knives in the ordinary cutter-heads so that theywill cut ex= actly in line is a matter of great delicacy and-"di'tliculty.

Another advantage arising from my construction is that the bits cannotbe driven or forced by knots or other unusual obstructions inward towardthe center of the head, for in the event of their being driven backwardthey simply slide in the annular groove and remain in their workingpositions. 7

Among other advantages incident to my mode of construction is theimportant one that the number of bits in the head may be' Y increased ordiminished at will, as demanded in practice by different kinds of workand different classes of wood. The construction also admits of bits orcutters of different kinds or forms being readily inserted and adjustedin the same head, so that in practice a single head or clamp may be usedfor a great variety of cutters.

In those heads in which the bits are adjustable to and from the centerit often happens that a knot will drive one cutter back and throw theentire work upon the others, but in my head this cannot happen.

By forming the tubular neck on one of the clamping-plates and threadingit to receive the nut, the device is cheapened and simplified, theordinary fastening-bolts dispensed with, and the plates held directlyopposite to each other..

vIt will be observed that the grooves a in the plates are of a V-form incross-section, and that the ribs or lips on the ends of the cutters areof a like form, so that when the plates are forced together the ribswedge fast in the grooves and hold the cutters very firmly.

I am aware that cutter-heads consisting of two solid semicircular blocksarranged eccentrically to each other, with their fiat sides in contactand secured together by means of rings seated in their sides, are old.And I am also aware that in metal-working cutters it is old to use aseries of small bits in a radially-slotted plate in combination with aflanged fastening-plate on the opposite side, and I wish it to beunderstood that I lay no claim thereto; but,

Having described my invention, what I do claim is 1. A cutter-head, inwhich the number of curved bits or cutters I), having their endsprovided with the ribs 1) to enter the grooves a, and their out ersurfaces curved in the arcs of circles eccentric to the ribs, as shownand described.

2. In a cutter-head for wood-working pur poses, the combination of twoclamping-plates, A A, provided with annular concentric grooves a andthin bits or cutters D, 'constructed and arranged in the peculiar mannershown and described.

3. The combination of the plate A, provided with the annular \l-shapedgroove 00, and the central neck having the exterior screw-thread, theplate A, provided with the annular groove a, the nut B, mounted on thecentral neck and turning loosely against the outside of the plate A, andthe cutting plates or blades D, provided with the i-shaped ribs 1),seated in the grooves a, and having their outer surfaces curved in thearcs of circles eccentric to the axis of the plates A A, as shown.

JOHN DU BOIS.

Witnesses:

Gno. R. VOSBURG, JAS. L. VOSBURG.

